Common rail fuel systems provide a way to introduce fuel into the combustion chambers of an engine. Typical common rail fuel systems include an injector having an actuating solenoid that opens a fuel nozzle when the solenoid is energized. Fuel is then injected into the combustion chamber as a function of the time period during which the solenoid remains energized and the pressure of fuel supplied to the fuel injector nozzle during that time period.
To optimize engine performance and exhaust emissions, engine manufacturers may vary the pressure of the fuel supplied to the fuel injector nozzle. One such example is described in U.S. Patent Application Publication No. 2004/0168673 (the '673 publication) by Shinogle published Sep. 2, 2004. The '673 publication describes a fuel system having a plurality of fuel injectors fluidly connectable to a first common rail holding a supply of fuel, and a second common rail holding a supply of actuation fluid. Each fuel injector of the '673 publication is equipped with an intensifier piston movable by the actuation fluid to increase the pressure of the fuel. By fluidly connecting a fuel injector to the first common rail, fuel can be sprayed from the injector at a first pressure. By fluidly connecting the injector to the first and second common rails, fuel can be sprayed from the injector at a second pressure that is higher than the first pressure.
Although the fuel injection system of the '673 publication may include multiple supplies of pressurized fluid that cooperate to adequately supply fuel to an engine at different pressures, it may, however, be complex and expensive. Specifically, because each fuel injector includes its own dedicated intensifier to vary the pressure of the fuel sprayed from that injector, the system may include a large number of components. This large number of components may increase the cost of the fuel injection system and the difficulty in precisely controlling the fuel system.
The fuel system of the present disclosure solves one or more of the problems set forth above.